The determination and the monitoring of physiological parameters such as body temperature and heart rate (HR) is of significance for athletes and especially for firemen, who are subject to high physical stress. Various methods, specifically optical acoustic and electric methods, are known for measuring the heart rate. Various measurement methods are likewise known for determining the body temperature, DE 100 38 247 C2 specifically showing a double temperature sensor for the determination of the body core temperature (Tc) from the calculation-based linkage between two temperatures measured on the patient. The calculation of the body core temperature (Tc) from a temperature Th1 measured immediately below the skin and a near-room temperature Th2 is known from DE 101 397 05 A1.
A sensor carrier that can be worn on the body with a temperature sensor, a sensor for measuring the heart rate and a communications interface is disclosed in JP 0 425 3839 A, in: Patent Abstracts of Japan. The prior-art sensors are usually arranged on different areas of the body and operate independently from one another.
The state of stress of the person being tested can be inferred from the linkage between the body temperature (Tc) and the heart rate (HR) by calculating a characteristic number, for example, PSI (Physiological Strain Index), see “Stress Evaluation by the Physiological Strain Index (PSI),” Daniel S. Moran, Journal of Basic and Clinical Physiology and Pharmacology, Vol. 11, 4, 2000.